In such strings of vehicles, in particular in tramways, it is in certain cases very important to lower as much as possible the floor of the vehicle. It is then not possible to use any more bogies with two or more axles. Preferably, wheel assemblies will then be used which carry only two wheels which will need to be guided in a suitable manner.
Such a string of articulated vehicles travelling on rails is known, in which the wheel assemblies are guided mechanically, by means of a guiding pulley cooperating with a side rail. This device requires the provision of an additional guiding rail and cannot therefore be implemented in all urban environments. Furthermore, the system is very expensive.